/*
 * Copyright 2015 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "src/gpu/ganesh/GrFragmentProcessor.h"

#include "include/core/SkM44.h"
#include "src/base/SkVx.h"
#include "src/core/SkRuntimeEffectPriv.h"
#include "src/gpu/KeyBuilder.h"
#include "src/gpu/ganesh/GrPipeline.h"
#include "src/gpu/ganesh/GrProcessorAnalysis.h"
#include "src/gpu/ganesh/GrShaderCaps.h"
#include "src/gpu/ganesh/effects/GrBlendFragmentProcessor.h"
#include "src/gpu/ganesh/effects/GrSkSLFP.h"
#include "src/gpu/ganesh/effects/GrTextureEffect.h"
#include "src/gpu/ganesh/glsl/GrGLSLFragmentShaderBuilder.h"
#include "src/gpu/ganesh/glsl/GrGLSLProgramBuilder.h"
#include "src/gpu/ganesh/glsl/GrGLSLProgramDataManager.h"
#include "src/gpu/ganesh/glsl/GrGLSLUniformHandler.h"

bool GrFragmentProcessor::isEqual(const GrFragmentProcessor &that) const
{
    if (this->classID() != that.classID()) {
        return false;
    }
    if (this->sampleUsage() != that.sampleUsage()) {
        return false;
    }
    if (!this->onIsEqual(that)) {
        return false;
    }
    if (this->numChildProcessors() != that.numChildProcessors()) {
        return false;
    }
    for (int i = 0; i < this->numChildProcessors(); ++i) {
        auto thisChild = this->childProcessor(i), thatChild = that.childProcessor(i);
        if (SkToBool(thisChild) != SkToBool(thatChild)) {
            return false;
        }
        if (thisChild && !thisChild->isEqual(*thatChild)) {
            return false;
        }
    }
    return true;
}

void GrFragmentProcessor::visitProxies(const GrVisitProxyFunc &func) const
{
    this->visitTextureEffects(
        [&func](const GrTextureEffect &te) { func(te.view().proxy(), te.samplerState().mipmapped()); });
}

void GrFragmentProcessor::visitTextureEffects(const std::function<void(const GrTextureEffect &)> &func) const
{
    if (auto *te = this->asTextureEffect()) {
        func(*te);
    }
    for (auto &child : fChildProcessors) {
        if (child) {
            child->visitTextureEffects(func);
        }
    }
}

void GrFragmentProcessor::visitWithImpls(const std::function<void(const GrFragmentProcessor &, ProgramImpl &)> &f,
    ProgramImpl &impl) const
{
    f(*this, impl);
    SkASSERT(impl.numChildProcessors() == this->numChildProcessors());
    for (int i = 0; i < this->numChildProcessors(); ++i) {
        if (const auto *child = this->childProcessor(i)) {
            child->visitWithImpls(f, *impl.childProcessor(i));
        }
    }
}

GrTextureEffect *GrFragmentProcessor::asTextureEffect()
{
    if (this->classID() == kGrTextureEffect_ClassID) {
        return static_cast<GrTextureEffect *>(this);
    }
    return nullptr;
}

const GrTextureEffect *GrFragmentProcessor::asTextureEffect() const
{
    if (this->classID() == kGrTextureEffect_ClassID) {
        return static_cast<const GrTextureEffect *>(this);
    }
    return nullptr;
}

#if defined(GR_TEST_UTILS)
static void recursive_dump_tree_info(const GrFragmentProcessor &fp, SkString indent, SkString *text)
{
    for (int index = 0; index < fp.numChildProcessors(); ++index) {
        text->appendf("\n%s(#%d) -> ", indent.c_str(), index);
        if (const GrFragmentProcessor *childFP = fp.childProcessor(index)) {
            text->append(childFP->dumpInfo());
            indent.append("\t");
            recursive_dump_tree_info(*childFP, indent, text);
        } else {
            text->append("null");
        }
    }
}

SkString GrFragmentProcessor::dumpTreeInfo() const
{
    SkString text = this->dumpInfo();
    recursive_dump_tree_info(*this, SkString("\t"), &text);
    text.append("\n");
    return text;
}
#endif

std::unique_ptr<GrFragmentProcessor::ProgramImpl> GrFragmentProcessor::makeProgramImpl() const
{
    std::unique_ptr<ProgramImpl> impl = this->onMakeProgramImpl();
    impl->fChildProcessors.push_back_n(fChildProcessors.size());
    for (int i = 0; i < fChildProcessors.size(); ++i) {
        impl->fChildProcessors[i] = fChildProcessors[i] ? fChildProcessors[i]->makeProgramImpl() : nullptr;
    }
    return impl;
}

int GrFragmentProcessor::numNonNullChildProcessors() const
{
    return std::count_if(fChildProcessors.begin(), fChildProcessors.end(), [](const auto &c) { return c != nullptr; });
}

#ifdef SK_DEBUG
bool GrFragmentProcessor::isInstantiated() const
{
    bool result = true;
    this->visitTextureEffects([&result](const GrTextureEffect &te) {
        if (!te.texture()) {
            result = false;
        }
    });
    return result;
}
#endif

void GrFragmentProcessor::registerChild(std::unique_ptr<GrFragmentProcessor> child, SkSL::SampleUsage sampleUsage)
{
    SkASSERT(sampleUsage.isSampled());

    if (!child) {
        fChildProcessors.push_back(nullptr);
        return;
    }

    // The child should not have been attached to another FP already and not had any sampling
    // strategy set on it.
    SkASSERT(!child->fParent && !child->sampleUsage().isSampled());

    // Configure child's sampling state first
    child->fUsage = sampleUsage;

    // Propagate the "will read dest-color" flag up to parent FPs.
    if (child->willReadDstColor()) {
        this->setWillReadDstColor();
    }

    // If this child receives passthrough or matrix transformed coords from its parent then note
    // that the parent's coords are used indirectly to ensure that they aren't omitted.
    if ((sampleUsage.isPassThrough() || sampleUsage.isUniformMatrix()) && child->usesSampleCoords()) {
        fFlags |= kUsesSampleCoordsIndirectly_Flag;
    }

    // Record that the child is attached to us; this FP is the source of any uniform data needed
    // to evaluate the child sample matrix.
    child->fParent = this;
    fChildProcessors.push_back(std::move(child));

    // Validate: our sample strategy comes from a parent we shouldn't have yet.
    SkASSERT(!fUsage.isSampled() && !fParent);
}

void GrFragmentProcessor::cloneAndRegisterAllChildProcessors(const GrFragmentProcessor &src)
{
    for (int i = 0; i < src.numChildProcessors(); ++i) {
        if (auto fp = src.childProcessor(i)) {
            this->registerChild(fp->clone(), fp->sampleUsage());
        } else {
            this->registerChild(nullptr);
        }
    }
}

std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::MakeColor(SkPMColor4f color)
{
    // Use ColorFilter signature/factory to get the constant output for constant input optimization
    static const SkRuntimeEffect *effect =
        SkMakeRuntimeEffect(SkRuntimeEffect::MakeForColorFilter, "uniform half4 color;"
        "half4 main(half4 inColor) { return color; }");
    SkASSERT(SkRuntimeEffectPriv::SupportsConstantOutputForConstantInput(effect));
    return GrSkSLFP::Make(effect, "color_fp", /* inputFP= */ nullptr,
        color.isOpaque() ? GrSkSLFP::OptFlags::kPreservesOpaqueInput : GrSkSLFP::OptFlags::kNone, "color", color);
}

std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::MulInputByChildAlpha(std::unique_ptr<GrFragmentProcessor> fp)
{
    if (!fp) {
        return nullptr;
    }
    return GrBlendFragmentProcessor::Make<SkBlendMode::kSrcIn>(/* src= */ nullptr, std::move(fp));
}

std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::ApplyPaintAlpha(std::unique_ptr<GrFragmentProcessor> child)
{
    SkASSERT(child);
    static const SkRuntimeEffect *effect =
        SkMakeRuntimeEffect(SkRuntimeEffect::MakeForColorFilter, "uniform colorFilter fp;"
        "half4 main(half4 inColor) {"
        "return fp.eval(inColor.rgb1) * inColor.a;"
        "}");
    return GrSkSLFP::Make(effect, "ApplyPaintAlpha", /* inputFP= */ nullptr,
        GrSkSLFP::OptFlags::kPreservesOpaqueInput | GrSkSLFP::OptFlags::kCompatibleWithCoverageAsAlpha, "fp",
        std::move(child));
}

std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::ModulateRGBA(std::unique_ptr<GrFragmentProcessor> inputFP,
    const SkPMColor4f &color)
{
    auto colorFP = MakeColor(color);
    return GrBlendFragmentProcessor::Make<SkBlendMode::kModulate>(std::move(colorFP), std::move(inputFP));
}

std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::ClampOutput(std::unique_ptr<GrFragmentProcessor> fp)
{
    SkASSERT(fp);
    static const SkRuntimeEffect *effect =
        SkMakeRuntimeEffect(SkRuntimeEffect::MakeForColorFilter, "half4 main(half4 inColor) {"
        "return saturate(inColor);"
        "}");
    SkASSERT(SkRuntimeEffectPriv::SupportsConstantOutputForConstantInput(effect));
    return GrSkSLFP::Make(effect, "Clamp", std::move(fp), GrSkSLFP::OptFlags::kPreservesOpaqueInput);
}

std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::SwizzleOutput(std::unique_ptr<GrFragmentProcessor> fp,
    const skgpu::Swizzle &swizzle)
{
    class SwizzleFragmentProcessor : public GrFragmentProcessor {
    public:
        static std::unique_ptr<GrFragmentProcessor> Make(std::unique_ptr<GrFragmentProcessor> fp,
            const skgpu::Swizzle &swizzle)
        {
            return std::unique_ptr<GrFragmentProcessor>(new SwizzleFragmentProcessor(std::move(fp), swizzle));
        }

        const char *name() const override
        {
            return "Swizzle";
        }

        std::unique_ptr<GrFragmentProcessor> clone() const override
        {
            return Make(this->childProcessor(0)->clone(), fSwizzle);
        }

    private:
        SwizzleFragmentProcessor(std::unique_ptr<GrFragmentProcessor> fp, const skgpu::Swizzle &swizzle)
            : INHERITED(kSwizzleFragmentProcessor_ClassID, ProcessorOptimizationFlags(fp.get())), fSwizzle(swizzle)
        {
            this->registerChild(std::move(fp));
        }

        std::unique_ptr<ProgramImpl> onMakeProgramImpl() const override
        {
            class Impl : public ProgramImpl {
            public:
                void emitCode(EmitArgs &args) override
                {
                    SkString childColor = this->invokeChild(0, args);

                    const SwizzleFragmentProcessor &sfp = args.fFp.cast<SwizzleFragmentProcessor>();
                    const skgpu::Swizzle &swizzle = sfp.fSwizzle;
                    GrGLSLFPFragmentBuilder *fragBuilder = args.fFragBuilder;

                    fragBuilder->codeAppendf("return %s.%s;", childColor.c_str(), swizzle.asString().c_str());
                }
            };
            return std::make_unique<Impl>();
        }

        void onAddToKey(const GrShaderCaps &, skgpu::KeyBuilder *b) const override
        {
            b->add32(fSwizzle.asKey());
        }

        bool onIsEqual(const GrFragmentProcessor &other) const override
        {
            const SwizzleFragmentProcessor &sfp = other.cast<SwizzleFragmentProcessor>();
            return fSwizzle == sfp.fSwizzle;
        }

        SkPMColor4f constantOutputForConstantInput(const SkPMColor4f &input) const override
        {
            return fSwizzle.applyTo(ConstantOutputForConstantInput(this->childProcessor(0), input));
        }

        skgpu::Swizzle fSwizzle;

        using INHERITED = GrFragmentProcessor;
    };

    if (!fp) {
        return nullptr;
    }
    if (skgpu::Swizzle::RGBA() == swizzle) {
        return fp;
    }
    return SwizzleFragmentProcessor::Make(std::move(fp), swizzle);
}

// ////////////////////////////////////////////////////////////////////////////

std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::OverrideInput(std::unique_ptr<GrFragmentProcessor> fp,
    const SkPMColor4f &color)
{
    if (!fp) {
        return nullptr;
    }
    static const SkRuntimeEffect *effect = SkMakeRuntimeEffect(SkRuntimeEffect::MakeForColorFilter,
        "uniform colorFilter fp;" // Declared as colorFilter so we can pass a color
        "uniform half4 color;"
        "half4 main(half4 inColor) {"
        "return fp.eval(color);"
        "}");
    return GrSkSLFP::Make(effect, "OverrideInput", /* inputFP= */ nullptr,
        color.isOpaque() ? GrSkSLFP::OptFlags::kPreservesOpaqueInput : GrSkSLFP::OptFlags::kNone, "fp", std::move(fp),
        "color", color);
}

// ////////////////////////////////////////////////////////////////////////////

std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::DisableCoverageAsAlpha(
    std::unique_ptr<GrFragmentProcessor> fp)
{
    if (!fp || !fp->compatibleWithCoverageAsAlpha()) {
        return fp;
    }
    static const SkRuntimeEffect *effect =
        SkMakeRuntimeEffect(SkRuntimeEffect::MakeForColorFilter, "half4 main(half4 inColor) { return inColor; }");
    SkASSERT(SkRuntimeEffectPriv::SupportsConstantOutputForConstantInput(effect));
    return GrSkSLFP::Make(effect, "DisableCoverageAsAlpha", std::move(fp), GrSkSLFP::OptFlags::kPreservesOpaqueInput);
}

// ////////////////////////////////////////////////////////////////////////////

std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::DestColor()
{
    static const SkRuntimeEffect *effect =
        SkMakeRuntimeEffect(SkRuntimeEffect::MakeForBlender, "half4 main(half4 src, half4 dst) {"
        "return dst;"
        "}");
    return GrSkSLFP::Make(effect, "DestColor", /* inputFP= */ nullptr, GrSkSLFP::OptFlags::kNone);
}

// ////////////////////////////////////////////////////////////////////////////

std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::Compose(std::unique_ptr<GrFragmentProcessor> f,
    std::unique_ptr<GrFragmentProcessor> g)
{
    class ComposeProcessor : public GrFragmentProcessor {
    public:
        static std::unique_ptr<GrFragmentProcessor> Make(std::unique_ptr<GrFragmentProcessor> f,
            std::unique_ptr<GrFragmentProcessor> g)
        {
            return std::unique_ptr<GrFragmentProcessor>(new ComposeProcessor(std::move(f), std::move(g)));
        }

        const char *name() const override
        {
            return "Compose";
        }

        std::unique_ptr<GrFragmentProcessor> clone() const override
        {
            return std::unique_ptr<GrFragmentProcessor>(new ComposeProcessor(*this));
        }

    private:
        std::unique_ptr<ProgramImpl> onMakeProgramImpl() const override
        {
            class Impl : public ProgramImpl {
            public:
                void emitCode(EmitArgs &args) override
                {
                    SkString result = this->invokeChild(1, args);        // g(x)
                    result = this->invokeChild(0, result.c_str(), args); // f(g(x))
                    args.fFragBuilder->codeAppendf("return %s;", result.c_str());
                }
            };
            return std::make_unique<Impl>();
        }

        ComposeProcessor(std::unique_ptr<GrFragmentProcessor> f, std::unique_ptr<GrFragmentProcessor> g)
            : INHERITED(kSeriesFragmentProcessor_ClassID, f->optimizationFlags() & g->optimizationFlags())
        {
            this->registerChild(std::move(f));
            this->registerChild(std::move(g));
        }

        ComposeProcessor(const ComposeProcessor &that) : INHERITED(that) {}

        void onAddToKey(const GrShaderCaps &, skgpu::KeyBuilder *) const override {}

        bool onIsEqual(const GrFragmentProcessor &) const override
        {
            return true;
        }

        SkPMColor4f constantOutputForConstantInput(const SkPMColor4f &inColor) const override
        {
            SkPMColor4f color = inColor;
            color = ConstantOutputForConstantInput(this->childProcessor(1), color);
            color = ConstantOutputForConstantInput(this->childProcessor(0), color);
            return color;
        }

        using INHERITED = GrFragmentProcessor;
    };

    // Allow either of the composed functions to be null.
    if (f == nullptr) {
        return g;
    }
    if (g == nullptr) {
        return f;
    }

    // Run an optimization pass on this composition.
    GrProcessorAnalysisColor inputColor;
    inputColor.setToUnknown();

    std::unique_ptr<GrFragmentProcessor> series[2] = {std::move(g), std::move(f)};
    GrColorFragmentProcessorAnalysis info(inputColor, series, std::size(series));

    SkPMColor4f knownColor;
    int leadingFPsToEliminate = info.initialProcessorsToEliminate(&knownColor);
    switch (leadingFPsToEliminate) {
        default:
            // We shouldn't eliminate more than we started with.
            SkASSERT(leadingFPsToEliminate <= 2);
            [[fallthrough]];
        case 0:
            // Compose the two processors as requested.
            return ComposeProcessor::Make(/* f= */ std::move(series[1]), /* g= */ std::move(series[0]));
        case 1:
            // Replace the first processor with a constant color.
            return ComposeProcessor::Make(/* f= */ std::move(series[1]),
                /* g= */ MakeColor(knownColor));
        case 2:
            // Replace the entire composition with a constant color.
            return MakeColor(knownColor);
    }
}

// ////////////////////////////////////////////////////////////////////////////

std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::ColorMatrix(std::unique_ptr<GrFragmentProcessor> child,
    const float matrix[20], bool unpremulInput, bool clampRGBOutput, bool premulOutput)
{
    static const SkRuntimeEffect *effect = SkMakeRuntimeEffect(SkRuntimeEffect::MakeForColorFilter,
        "uniform half4x4 m;"
        "uniform half4 v;"
        "uniform int unpremulInput;"  // always specialized
        "uniform int clampRGBOutput;" // always specialized
        "uniform int premulOutput;"   // always specialized
        "half4 main(half4 color) {"
        "if (bool(unpremulInput)) {"
        "color = unpremul(color);"
        "}"
        "color = m * color + v;"
        "if (bool(clampRGBOutput)) {"
        "color = saturate(color);"
        "} else {"
        "color.a = saturate(color.a);"
        "}"
        "if (bool(premulOutput)) {"
        "color.rgb *= color.a;"
        "}"
        "return color;"
        "}");
    SkASSERT(SkRuntimeEffectPriv::SupportsConstantOutputForConstantInput(effect));

    SkM44 m44(matrix[0], matrix[1], matrix[2], matrix[3], matrix[5], matrix[6], matrix[7], matrix[8], matrix[10],
        matrix[11], matrix[12], matrix[13], matrix[15], matrix[16], matrix[17], matrix[18]);
    SkV4 v4 = { matrix[4], matrix[9], matrix[14], matrix[19] };
    return GrSkSLFP::Make(effect, "ColorMatrix", std::move(child), GrSkSLFP::OptFlags::kNone, "m", m44, "v", v4,
        "unpremulInput", GrSkSLFP::Specialize(unpremulInput ? 1 : 0), "clampRGBOutput",
        GrSkSLFP::Specialize(clampRGBOutput ? 1 : 0), "premulOutput", GrSkSLFP::Specialize(premulOutput ? 1 : 0));
}

// ////////////////////////////////////////////////////////////////////////////

std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::SurfaceColor()
{
    class SurfaceColorProcessor : public GrFragmentProcessor {
    public:
        static std::unique_ptr<GrFragmentProcessor> Make()
        {
            return std::unique_ptr<GrFragmentProcessor>(new SurfaceColorProcessor());
        }

        std::unique_ptr<GrFragmentProcessor> clone() const override
        {
            return Make();
        }

        const char *name() const override
        {
            return "SurfaceColor";
        }

    private:
        std::unique_ptr<ProgramImpl> onMakeProgramImpl() const override
        {
            class Impl : public ProgramImpl {
            public:
                void emitCode(EmitArgs &args) override
                {
                    const char *dstColor = args.fFragBuilder->dstColor();
                    args.fFragBuilder->codeAppendf("return %s;", dstColor);
                }
            };
            return std::make_unique<Impl>();
        }

        SurfaceColorProcessor() : INHERITED(kSurfaceColorProcessor_ClassID, kNone_OptimizationFlags)
        {
            this->setWillReadDstColor();
        }

        void onAddToKey(const GrShaderCaps &, skgpu::KeyBuilder *) const override {}

        bool onIsEqual(const GrFragmentProcessor &) const override
        {
            return true;
        }

        using INHERITED = GrFragmentProcessor;
    };

    return SurfaceColorProcessor::Make();
}

// ////////////////////////////////////////////////////////////////////////////

std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::DeviceSpace(std::unique_ptr<GrFragmentProcessor> fp)
{
    if (!fp) {
        return nullptr;
    }

    class DeviceSpace : GrFragmentProcessor {
    public:
        static std::unique_ptr<GrFragmentProcessor> Make(std::unique_ptr<GrFragmentProcessor> fp)
        {
            return std::unique_ptr<GrFragmentProcessor>(new DeviceSpace(std::move(fp)));
        }

    private:
        DeviceSpace(std::unique_ptr<GrFragmentProcessor> fp)
            : GrFragmentProcessor(kDeviceSpace_ClassID, fp->optimizationFlags())
        {
            // Passing FragCoord here is the reason this is a subclass and not a runtime-FP.
            this->registerChild(std::move(fp), SkSL::SampleUsage::FragCoord());
        }

        std::unique_ptr<GrFragmentProcessor> clone() const override
        {
            auto child = this->childProcessor(0)->clone();
            return std::unique_ptr<GrFragmentProcessor>(new DeviceSpace(std::move(child)));
        }

        SkPMColor4f constantOutputForConstantInput(const SkPMColor4f &f) const override
        {
            return this->childProcessor(0)->constantOutputForConstantInput(f);
        }

        std::unique_ptr<ProgramImpl> onMakeProgramImpl() const override
        {
            class Impl : public ProgramImpl {
            public:
                Impl() = default;
                void emitCode(ProgramImpl::EmitArgs &args) override
                {
                    auto child = this->invokeChild(0, args.fInputColor, args, "sk_FragCoord.xy");
                    args.fFragBuilder->codeAppendf("return %s;", child.c_str());
                }
            };
            return std::make_unique<Impl>();
        }

        void onAddToKey(const GrShaderCaps &, skgpu::KeyBuilder *) const override {}

        bool onIsEqual(const GrFragmentProcessor &processor) const override
        {
            return true;
        }

        const char *name() const override
        {
            return "DeviceSpace";
        }
    };

    return DeviceSpace::Make(std::move(fp));
}

// ////////////////////////////////////////////////////////////////////////////

#define CLIP_EDGE_SKSL                  \
    "const int kFillBW = 0;"            \
        "const int kFillAA = 1;"        \
        "const int kInverseFillBW = 2;" \
        "const int kInverseFillAA = 3;"

static_assert(static_cast<int>(GrClipEdgeType::kFillBW) == 0);
static_assert(static_cast<int>(GrClipEdgeType::kFillAA) == 1);
static_assert(static_cast<int>(GrClipEdgeType::kInverseFillBW) == 2);
static_assert(static_cast<int>(GrClipEdgeType::kInverseFillAA) == 3);

std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::Rect(std::unique_ptr<GrFragmentProcessor> inputFP,
    GrClipEdgeType edgeType, SkRect rect)
{
    static const SkRuntimeEffect *effect = SkMakeRuntimeEffect(SkRuntimeEffect::MakeForShader,
        CLIP_EDGE_SKSL "uniform int edgeType;" // GrClipEdgeType, specialized
        "uniform float4 rectUniform;"

        "half4 main(float2 xy) {"
        "half coverage;"
        "if (edgeType == kFillBW || edgeType == kInverseFillBW) {"
        // non-AA
        "coverage = half(all(greaterThan(float4(sk_FragCoord.xy, rectUniform.zw),"
        "float4(rectUniform.xy, sk_FragCoord.xy))));"
        "} else {"
        // compute coverage relative to left and right edges, add, then subtract 1 to
        // account for double counting. And similar for top/bottom.
        "half4 dists4 = saturate(half4(1, 1, -1, -1) *"
        "half4(sk_FragCoord.xyxy - rectUniform));"
        "half2 dists2 = dists4.xy + dists4.zw - 1;"
        "coverage = dists2.x * dists2.y;"
        "}"

        "if (edgeType == kInverseFillBW || edgeType == kInverseFillAA) {"
        "coverage = 1.0 - coverage;"
        "}"

        "return half4(coverage);"
        "}");

    SkASSERT(rect.isSorted());
    // The AA math in the shader evaluates to 0 at the uploaded coordinates, so outset by 0.5
    // to interpolate from 0 at a half pixel inset and 1 at a half pixel outset of rect.
    SkRect rectUniform = GrClipEdgeTypeIsAA(edgeType) ? rect.makeOutset(.5f, .5f) : rect;

    auto rectFP =
        GrSkSLFP::Make(effect, "Rect", /* inputFP= */ nullptr, GrSkSLFP::OptFlags::kCompatibleWithCoverageAsAlpha,
        "edgeType", GrSkSLFP::Specialize(static_cast<int>(edgeType)), "rectUniform", rectUniform);
    return GrBlendFragmentProcessor::Make<SkBlendMode::kModulate>(std::move(rectFP), std::move(inputFP));
}

GrFPResult GrFragmentProcessor::Circle(std::unique_ptr<GrFragmentProcessor> inputFP, GrClipEdgeType edgeType,
    SkPoint center, float radius)
{
    // A radius below half causes the implicit insetting done by this processor to become
    // inverted. We could handle this case by making the processor code more complicated.
    if (radius < .5f && GrClipEdgeTypeIsInverseFill(edgeType)) {
        return GrFPFailure(std::move(inputFP));
    }

    static const SkRuntimeEffect *effect = SkMakeRuntimeEffect(SkRuntimeEffect::MakeForShader,
        CLIP_EDGE_SKSL "uniform int edgeType;" // GrClipEdgeType, specialized
        // The circle uniform is (center.x, center.y, radius + 0.5, 1 / (radius + 0.5)) for regular
        // fills and (..., radius - 0.5, 1 / (radius - 0.5)) for inverse fills.
        "uniform float4 circle;"

        "half4 main(float2 xy) {"
        // TODO: Right now the distance to circle calculation is performed in a space normalized
        // to the radius and then denormalized. This is to mitigate overflow on devices that
        // don't have full float.
        "half d;"
        "if (edgeType == kInverseFillBW || edgeType == kInverseFillAA) {"
        "d = half((length((circle.xy - sk_FragCoord.xy) * circle.w) - 1.0) * circle.z);"
        "} else {"
        "d = half((1.0 - length((circle.xy - sk_FragCoord.xy) * circle.w)) * circle.z);"
        "}"
        "return half4((edgeType == kFillAA || edgeType == kInverseFillAA)"
        "? saturate(d)"
        ": (d > 0.5 ? 1 : 0));"
        "}");

    SkScalar effectiveRadius = radius;
    if (GrClipEdgeTypeIsInverseFill(edgeType)) {
        effectiveRadius -= 0.5f;
        // When the radius is 0.5 effectiveRadius is 0 which causes an inf * 0 in the shader.
        effectiveRadius = std::max(0.001f, effectiveRadius);
    } else {
        effectiveRadius += 0.5f;
    }
    SkV4 circle = { center.fX, center.fY, effectiveRadius, SkScalarInvert(effectiveRadius) };

    auto circleFP =
        GrSkSLFP::Make(effect, "Circle", /* inputFP= */ nullptr, GrSkSLFP::OptFlags::kCompatibleWithCoverageAsAlpha,
        "edgeType", GrSkSLFP::Specialize(static_cast<int>(edgeType)), "circle", circle);
    return GrFPSuccess(GrBlendFragmentProcessor::Make<SkBlendMode::kModulate>(std::move(inputFP), std::move(circleFP)));
}

GrFPResult GrFragmentProcessor::Ellipse(std::unique_ptr<GrFragmentProcessor> inputFP, GrClipEdgeType edgeType,
    SkPoint center, SkPoint radii, const GrShaderCaps &caps)
{
    const bool medPrecision = !caps.fFloatIs32Bits;

    // Small radii produce bad results on devices without full float.
    if (medPrecision && (radii.fX < 0.5f || radii.fY < 0.5f)) {
        return GrFPFailure(std::move(inputFP));
    }
    // Very narrow ellipses produce bad results on devices without full float
    if (medPrecision && (radii.fX > 255 * radii.fY || radii.fY > 255 * radii.fX)) {
        return GrFPFailure(std::move(inputFP));
    }
    // Very large ellipses produce bad results on devices without full float
    if (medPrecision && (radii.fX > 16384 || radii.fY > 16384)) {
        return GrFPFailure(std::move(inputFP));
    }

    static const SkRuntimeEffect *effect = SkMakeRuntimeEffect(SkRuntimeEffect::MakeForShader,
        CLIP_EDGE_SKSL "uniform int edgeType;" // GrClipEdgeType, specialized
        "uniform int medPrecision;"            // !sk_Caps.floatIs32Bits, specialized

        "uniform float4 ellipse;"
        "uniform float2 scale;" // only for medPrecision

        "half4 main(float2 xy) {"
        // d is the offset to the ellipse center
        "float2 d = sk_FragCoord.xy - ellipse.xy;"
        // If we're on a device with a "real" mediump then we'll do the distance computation in
        // a space that is normalized by the larger radius or 128, whichever is smaller. The
        // scale uniform will be scale, 1/scale. The inverse squared radii uniform values are
        // already in this normalized space. The center is not.
        "if (bool(medPrecision)) {"
        "d *= scale.y;"
        "}"
        "float2 Z = d * ellipse.zw;"
        // implicit is the evaluation of (x/rx)^2 + (y/ry)^2 - 1.
        "float implicit = dot(Z, d) - 1;"
        // grad_dot is the squared length of the gradient of the implicit.
        "float grad_dot = 4 * dot(Z, Z);"
        // Avoid calling inversesqrt on zero.
        "if (bool(medPrecision)) {"
        "grad_dot = max(grad_dot, 6.1036e-5);"
        "} else {"
        "grad_dot = max(grad_dot, 1.1755e-38);"
        "}"
        "float approx_dist = implicit * inversesqrt(grad_dot);"
        "if (bool(medPrecision)) {"
        "approx_dist *= scale.x;"
        "}"

        "half alpha;"
        "if (edgeType == kFillBW) {"
        "alpha = approx_dist > 0.0 ? 0.0 : 1.0;"
        "} else if (edgeType == kFillAA) {"
        "alpha = saturate(0.5 - half(approx_dist));"
        "} else if (edgeType == kInverseFillBW) {"
        "alpha = approx_dist > 0.0 ? 1.0 : 0.0;"
        "} else {" // edgeType == kInverseFillAA
        "alpha = saturate(0.5 + half(approx_dist));"
        "}"
        "return half4(alpha);"
        "}");

    float invRXSqd;
    float invRYSqd;
    SkV2 scale = { 1, 1 };
    // If we're using a scale factor to work around precision issues, choose the larger radius as
    // the scale factor. The inv radii need to be pre-adjusted by the scale factor.
    if (medPrecision) {
        if (radii.fX > radii.fY) {
            invRXSqd = 1.f;
            invRYSqd = (radii.fX * radii.fX) / (radii.fY * radii.fY);
            scale = { radii.fX, 1.f / radii.fX };
        } else {
            invRXSqd = (radii.fY * radii.fY) / (radii.fX * radii.fX);
            invRYSqd = 1.f;
            scale = { radii.fY, 1.f / radii.fY };
        }
    } else {
        invRXSqd = 1.f / (radii.fX * radii.fX);
        invRYSqd = 1.f / (radii.fY * radii.fY);
    }
    SkV4 ellipse = { center.fX, center.fY, invRXSqd, invRYSqd };

    auto ellipseFP =
        GrSkSLFP::Make(effect, "Ellipse", /* inputFP= */ nullptr, GrSkSLFP::OptFlags::kCompatibleWithCoverageAsAlpha,
        "edgeType", GrSkSLFP::Specialize(static_cast<int>(edgeType)), "medPrecision",
        GrSkSLFP::Specialize<int>(medPrecision), "ellipse", ellipse, "scale", scale);
    return GrFPSuccess(
        GrBlendFragmentProcessor::Make<SkBlendMode::kModulate>(std::move(ellipseFP), std::move(inputFP)));
}

// ////////////////////////////////////////////////////////////////////////////

std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::HighPrecision(std::unique_ptr<GrFragmentProcessor> fp)
{
    class HighPrecisionFragmentProcessor : public GrFragmentProcessor {
    public:
        static std::unique_ptr<GrFragmentProcessor> Make(std::unique_ptr<GrFragmentProcessor> fp)
        {
            return std::unique_ptr<GrFragmentProcessor>(new HighPrecisionFragmentProcessor(std::move(fp)));
        }

        const char *name() const override
        {
            return "HighPrecision";
        }

        std::unique_ptr<GrFragmentProcessor> clone() const override
        {
            return Make(this->childProcessor(0)->clone());
        }

    private:
        HighPrecisionFragmentProcessor(std::unique_ptr<GrFragmentProcessor> fp)
            : INHERITED(kHighPrecisionFragmentProcessor_ClassID, ProcessorOptimizationFlags(fp.get()))
        {
            this->registerChild(std::move(fp));
        }

        std::unique_ptr<ProgramImpl> onMakeProgramImpl() const override
        {
            class Impl : public ProgramImpl {
            public:
                void emitCode(EmitArgs &args) override
                {
                    SkString childColor = this->invokeChild(0, args);

                    args.fFragBuilder->forceHighPrecision();
                    args.fFragBuilder->codeAppendf("return %s;", childColor.c_str());
                }
            };
            return std::make_unique<Impl>();
        }

        void onAddToKey(const GrShaderCaps &, skgpu::KeyBuilder *) const override {}
        bool onIsEqual(const GrFragmentProcessor &other) const override
        {
            return true;
        }

        SkPMColor4f constantOutputForConstantInput(const SkPMColor4f &input) const override
        {
            return ConstantOutputForConstantInput(this->childProcessor(0), input);
        }

        using INHERITED = GrFragmentProcessor;
    };

    return HighPrecisionFragmentProcessor::Make(std::move(fp));
}

// ////////////////////////////////////////////////////////////////////////////

using ProgramImpl = GrFragmentProcessor::ProgramImpl;

void ProgramImpl::setData(const GrGLSLProgramDataManager &pdman, const GrFragmentProcessor &processor)
{
    this->onSetData(pdman, processor);
}

SkString ProgramImpl::invokeChild(int childIndex, const char *inputColor, const char *destColor, EmitArgs &args,
    std::string_view skslCoords)
{
    SkASSERT(childIndex >= 0);

    if (!inputColor) {
        inputColor = args.fInputColor;
    }

    const GrFragmentProcessor *childProc = args.fFp.childProcessor(childIndex);
    if (!childProc) {
        // If no child processor is provided, return the input color as-is.
        return SkString(inputColor);
    }

    auto invocation = SkStringPrintf("%s(%s", this->childProcessor(childIndex)->functionName(), inputColor);

    if (childProc->isBlendFunction()) {
        if (!destColor) {
            destColor = args.fFp.isBlendFunction() ? args.fDestColor : "half4(1)";
        }
        invocation.appendf(", %s", destColor);
    }

    // Assert that the child has no sample matrix. A uniform matrix sample call would go through
    // invokeChildWithMatrix, not here.
    SkASSERT(!childProc->sampleUsage().isUniformMatrix());

    if (args.fFragBuilder->getProgramBuilder()->fragmentProcessorHasCoordsParam(childProc)) {
        SkASSERT(!childProc->sampleUsage().isFragCoord() || skslCoords == "sk_FragCoord.xy");
        // The child's function takes a half4 color and a float2 coordinate
        if (!skslCoords.empty()) {
            invocation.appendf(", %.*s", (int)skslCoords.size(), skslCoords.data());
        } else {
            invocation.appendf(", %s", args.fSampleCoord);
        }
    }

    invocation.append(")");
    return invocation;
}

SkString ProgramImpl::invokeChildWithMatrix(int childIndex, const char *inputColor, const char *destColor,
    EmitArgs &args)
{
    SkASSERT(childIndex >= 0);

    if (!inputColor) {
        inputColor = args.fInputColor;
    }

    const GrFragmentProcessor *childProc = args.fFp.childProcessor(childIndex);
    if (!childProc) {
        // If no child processor is provided, return the input color as-is.
        return SkString(inputColor);
    }

    SkASSERT(childProc->sampleUsage().isUniformMatrix());

    // Every uniform matrix has the same (initial) name. Resolve that into the mangled name:
    GrShaderVar uniform =
        args.fUniformHandler->getUniformMapping(args.fFp, SkString(SkSL::SampleUsage::MatrixUniformName()));
    SkASSERT(uniform.getType() == SkSLType::kFloat3x3);
    const SkString &matrixName(uniform.getName());

    auto invocation = SkStringPrintf("%s(%s", this->childProcessor(childIndex)->functionName(), inputColor);

    if (childProc->isBlendFunction()) {
        if (!destColor) {
            destColor = args.fFp.isBlendFunction() ? args.fDestColor : "half4(1)";
        }
        invocation.appendf(", %s", destColor);
    }

    // Produce a string containing the call to the helper function. We have a uniform variable
    // containing our transform (matrixName). If the parent coords were produced by uniform
    // transforms, then the entire expression (matrixName * coords) is lifted to a vertex shader
    // and is stored in a varying. In that case, childProc will not be sampled explicitly, so its
    // function signature will not take in coords.
    //
    // In all other cases, we need to insert sksl to compute matrix * parent coords and then invoke
    // the function.
    if (args.fFragBuilder->getProgramBuilder()->fragmentProcessorHasCoordsParam(childProc)) {
        // Only check perspective for this specific matrix transform, not the aggregate FP property.
        // Any parent perspective will have already been applied when evaluated in the FS.
        if (childProc->sampleUsage().hasPerspective()) {
            invocation.appendf(", proj((%s) * %s.xy1)", matrixName.c_str(), args.fSampleCoord);
        } else if (args.fShaderCaps->fNonsquareMatrixSupport) {
            invocation.appendf(", float3x2(%s) * %s.xy1", matrixName.c_str(), args.fSampleCoord);
        } else {
            invocation.appendf(", ((%s) * %s.xy1).xy", matrixName.c_str(), args.fSampleCoord);
        }
    }

    invocation.append(")");
    return invocation;
}
